Coextrusion binder, its use for a multilayer structure and the structure thus obtained

ABSTRACT

The present invention relates to a coextrusion binder comprising: 
     5 to 30 parts of a polymer (A), itself comprising a blend of a polyethylene (A1) of relative density between 0.935 and 0.980 and of a polymer (A2) chosen from elastomers, very low-density polyethylenes and ethylene copolymers, the (A1)+(A2) blend being cografted with an unsaturated carboxylic acid; 
     95 to 70 parts of a polyethylene (B) of relative density between 0.930 and 0.950; 
     the blend of (A) and (B) being such that: 
     its relative density is between 0.930 and 0.950, 
     the content of grafted unsaturated carboxylic acid is between 30 and 10,000 ppm, 
     the MFI (melt flow index) measured according to ASTM D 1238 at 190° C./21.6 kg is between 5 and 100. 
     This binder is particularly useful for petrol tanks of structure: HDPE/binder/EVOH or PA/binder/HDPE.

CROSS REFERENCE TO RELATED APPLICATION

This application is related to a concurrently filed applicationentitled, “Coextrusion Binder, Its Use For A Multilayer Structure AndThe Structure Thus Obtained” the inventors being, Jean-Claude Jammet,Christophe Le Roy, Xavier Marical and Jérôme Pascal, Attorney DocketNumber ATOCM-172, based on priority French application 99/04261 filedApr. 6, 1999, said application b orated by reference herein.

FIELD OF THE INVENTION

The present invention relates to a coextrusion binder, to its use formaking a multilayer structure and to the structure thus obtained.

SUMMARY OF THE INVENTION

More specifically, the coextrusion binder of the present inventioncomprises:

5 to 30 parts of a polymer (A), itself comprising a blend of apolyethylene (A1) of relative density between 0.935 and 0.980 and of apolymer (A2) chosen from elastomers, very low-density polyethylenes andethylene copolymers, the (A1)+(A2) blend being cografted with anunsaturated carboxylic acid;

95 to 70 parts of a polyethylene (B) of relative density between 0.930and 0.950;

the blend of (A) and (B) being such that:

its relative density is between 0.930 and 0.950,

the content of grafted unsaturated carboxylic acid is between 30 and10,000 ppm,

the MFI (melt flow index) measured according to ASTM D 1238 at 190°C./21.6 kg is between 5 and 100.

The present invention also relates to a multilayer structure comprisinga layer which comprises the coextrusion binder defined above and,directly attached to the latter, a layer (E) of a nitrogen-containing oroxygen-containing polar resin, such as a layer of a polyamide resin, ofan aliphatic polyketone, of a saponified ethylene-vinyl acetatecopolymer (EVOH) or of a polyester resin, or else a metal layer.

The invention also relates to a structure comprising the above structureand, directly attached to the latter on the binder side, either apolyolefin layer (F) or a layer of a resin chosen from the resins of thelayer (E), or else a metal layer.

The invention also relates to a structure comprising, respectively, apolyolefin layer (F), a layer of the binder defined above, a layer of apolyamide resin or of a saponified ethylene-vinyl acetate copolymer(EVOH), a layer of the binder defined above and a polyolefin layer (F).

These structures are useful for manufacturing flexible or rigidpackages, such as sachets, bottles or containers. These packages may bemanufactured by coextrusion, lamination or coextrusion-blow moulding.

The invention is useful in particular for coextruded hoses or pipes andfor motor-vehicle petrol tanks.

Petrol tanks usually consist of five layers consisting respectively of:

high-density polyethylene (HDPE);

a binder;

a <polyamide (PA) or a copolymer having ethylene units and vinyl alcoholunits (EVOH);

a binder;

HDPE.

Very often, a sixth layer is added between one of the binder layers andone of the HDPE layers. This sixth layer consists of manufacturing scrapresulting from the moulding of the tanks or, for a much smallerquantity, tanks which are off-specification. This scrap and theseoff-specification tanks are ground up in order to obtain granules. Thisregrind is then remelted and extruded directly on the plant forcoextruding the tanks. This regrind could also be melted andregranulated by an extrusion machine, such as a twin-screw extruder,before it is reused.

According to a variant, the recycled product may be blended with theHDPE of the two outermost layers of the tank. It is also possible, forexample, to blend the granules of recycled product with the virgin HDPEgranules of these two layers. Any combination of these recyclingoperations may also be used.

The amount of recycled material may represent up to 50% of the totalweight of the tank.

This sixth layer therefore includes all the materials of the multilayerstructure, namely HDPE, binders, PA or EVOH.

BACKGROUND OF THE INVENTION

The prior art has already described multilayer petrol tanks. EP 834,415describes structures comprising:

Polyethylene/Binder/EVOH/Binder/Polyethylene.

The binder is a maleic-anhydride-grafted polyethylene having an MFI of0.1 to 3 and a relative density between 0.920 and 0.930 and it contains2 to 40% by weight of material insoluble in n-decane at 90° C. It isexplained that the grafted polyethylene is dissolved in n-decane at 140°C. and cooled to 90° C., at which temperature products precipitate; itis then filtered and the insoluble content is the percentage by weightwhich precipitates and is collected by filtration at 90° C.

If the content is between 2 and 40%, the binder has good petrolresistance.

No example shows such a polymer. The text specifies that the binder isin fact a blend of 2 to 30 parts of a grafted polyethylene having arelative density between 0.930 and 0.980 and of 70 to 98 parts of anungrafted polyethylene having a relative density between 0.910 and0.940, preferably 0.915 and 0.935.

An attempt has been made to prepare binders and the correspondingstructures in accordance with this teaching. It has found that thebinders were not reproducible, that is to say the choice of the productby its relative density is not a sufficient indication.

It has also been found that these criteria were not sufficient for thebinder to withstand petrol,

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described in detail.

With regard to the polymer (A1), this is a polyethylene homopolymer or acopolymer of ethylene with a comonomer chosen, for example, from:

α-olefins, advantageously those having from 3 to 30 carbon atoms.Examples of α-olefins having 3 to 30 carbon atoms as possible comonomerscomprise propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene,4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene,1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicocene, 1-dococene,1-tetracocene, 1-hexacocene, 1-octacocene and 1-triacontene. Theseα-olefins may be used by themselves or as a blend of two or more ofthem;

the esters of unsaturated carboxylic acids, such as, for example, alkyl(meth)acrylates, the alkyl of which has from 1 to 24 carbon atoms.Examples of alkyl acrylates or methacrylates that can be used are, inparticular, methyl methacrylate, ethyl acrylate, n-butyl acrylate,isobutyl acrylate and 2-ethylhexyl acrylate;

the vinyl esters of saturated carboxylic acids, such as, for example,vinyl acetate or vinyl propionate.

Advantageously, (A1) is a high-density polyethylene (HDPE) of relativedensity between 0.940 and 0.965.

The MFI of (A1) is between 0.1 and 3 at 2.16 kg.

The copolymer (A2) may, for example, be an ethylene/propylene elastomer(EPR) or an ethylene/propylene/diene elastomer (EPDM).

(A2) may also be a very low-density polyethylene (VLDPE) which is eitheran ethylene homopolymer or an ethylene/α-olefin copolymer.

(A2) may also be a copolymer of ethylene with at least one productchosen from (i) unsaturated carboxylic acids, their salts and theiresters, (ii) vinyl esters of saturated carboxylic acids and (iii)unsaturated dicarboxylic acids, their salts, their esters, theirhalf-esters and their anhydrides.

(A2) may be a metallocene polyethylene.

The amounts of (A1) and (A2) are advantageously 60 to 95 parts of (A1)for 40 to 5 parts of (A2).

The blend of (A1) and (A2) is grafted with an unsaturated carboxylicacid, that is to say (A1) and (A2) are cografted. It would not beoutside the scope of the invention to use a functional derivative ofthis acid.

Examples of unsaturated carboxylic acids are those having 2 to 20 carbonatoms, such as acrylic, methacrylic, maleic, fumaric and itaconic acids.The functional derivatives of these acids comprise, for example,anhydrides, ester derivatives, amide derivatives, imide derivatives andmetal salts (such as alkali metal salts) of unsaturated carboxylicacids.

Unsaturated dicarboxylic acids having 4 to 10 carbon atoms and theirfunctional derivatives, particularly their anhydrides, are particularlypreferred grafting monomers.

These grafting monomers comprise, for example, maleic, fumaric,itaconic, citraconic, allylsuccinic, cyclohex-4-ene-1,2-dicarboxylic,4-methylcyclohex-4-ene-1,2-dicarboxylic,bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic andx-methylbicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acids and maleic,itaconic, citraconic, allylsuccinic, cyclohex-4-ene-1,2-dicarboxylic,4-methylenecyclohex-4-ene-1,2-dicarboxylic,bicyclo-[2.2.1]hept-5-ene-2,3-dicarboxylic andx-methyl-bicyclo[2.2.1]hept-5-ene-2,2-dicarboxylic anhydrides.

Examples of other grafting monomers comprise C₁-C₈ alkyl esters orglycidyl ester derivatives of unsaturated carboxylic acids, such asmethyl acrylate, methyl methacrylate, ethyl acrylate, ethylmethacrylate, butyl acrylate, butyl methacrylate, glycidyl acrylate,glycidyl methacrylate, monoethyl maleate, diethyl maleate, monoethylfumarate, dimethyl fumarate, monomethyl itaconate and diethyl itaconate;amide derivatives of unsaturated carboxylic acids, such as acrylamide,methacrylamide, the monoamide of maleic acid, the diamide of maleicacid, the N-monoethylamide of maleic acid, the N,N-diethylamide ofmaleic acid, the N-monobutylamide of maleic acid, the N,N-dibutylamideof maleic acid, the monoamide of fumaric acid, the diamide of fumaricacid, the N-mono-ethylamide of fumaric acid, the N,N-diethylamide offumaric acid, the N-monobutylamide of fumaric acid and theN,N-dibutylamide of fumaric acid; imide derivatives of unsaturatedcarboxylic acids, such as maleimide, N-butylmaleimide,N-phenylmaleimide; and metal salts of unsaturated carboxylic acids, suchas sodium acrylate, sodium methacrylate, potassium acrylate andpotassium methacrylate. Maleic anhydride is preferred.

Various known processes may be used to graft a grafting monomer onto theblend of (A1) and (A2).The blend can contain at levels between 10 ppmand 5% additives generaly used for processing of polyolefins and such asantioxidants based on substituted phenolic molecules etc., anti UVagents, processing aids such as fatty amides, stearic acid and salt ofstearic acid, fluorinated polymers known to prevent extrusion defaults,anti fog agents based on amines, antiblocking agents such as silica ortalc, master batches with dyes, nucleating agents etc.

For example, this may be carried out by heating the polymers (A1) and(A2) to high temperatures, approximately 150 to approximately 300° C.,in the presence or absence of a solvent and with or without a radicalinitiator. Suitable solvents that may be used in this reaction arebenzene, toluene, xylene, chlorobenzene, cumene, etc. Suitable radicalinitiators which can be used comprise tert-butyl hydroperoxide, cumenehydroperoxide, diisopropylbenzene hydroperoxide, di-tert-butyl peroxide,tert-butylcumyl peroxide, dicumyl peroxide,1,3-bis(tert-butylperoxyisopropyl)-benzene, acetyl peroxide, benzoylperoxide, isobutyryl peroxide, bis(3,5,5-trimethylhexanoyl) peroxide andmethyl ethyl ketone peroxide.

The amount of grafting monomer in the blend of (A1) and (A2) modified bythe grafting obtained in the abovementioned manner may be chosen in anappropriate manner, but it is preferably 0.01 to 10%, better still 600ppm to 6%, with respect to the weight of grafted (A1) and (A2).

The amount of grafted monomer is determined by assaying the succinicfunctional groups by FTIR spectroscopy.

The MFI of (A), that is to say of (A1)and (A2) which have beencografted, is 5 to 100/21.6 kg. As regards the polyethylene (B), this isan ethylene homopolymer or copolymer.

The relative density of (B) is advantageously between 0.930 and 0.940.

The MFI of (B):5 to 100/21.6 kg.

According to one advantageous form of the invention, the bindercomprises 5 to 20 parts of (A) per 95 to 80 parts of (B).

The relative density of the blend (A)+(B) is advantageously between0.930 and 0.940.

The multilayer structure of the present invention consists of the layercomprising the above binder and of a layer (E) of oxygen-containing ornitrogen-containing polar resin, or a metal layer.

Examples of preferred polar resins in the layer other than the binderare polyamide resins, an aliphatic polyketone, a saponifiedethylene-vinyl acetate copolymer and polyesters.

More specifically, they comprise long-chain synthetic polyamides havingstructural units of the amide group in the main chain, such as PA-6,PA-6,6, PA-6,10, PA-11, PA-6/6,6 and PA-12; a saponified ethylene-vinylacetate copolymer having a degree of saponification of approximately 90to 100 mol %, obtained by saponifying an ethylene/vinyl acetatecopolymer having an ethylene content of approximately 15 to 60 mol %;polyesters such as polyethylene terephthalate, polybutylene terphthalateand polyethylene naphthenate, blends of these resins, or else aromaticpolyesters such as liquid-crystal polymers.

The metal layer may, for example, be a sheet, a film or a foil of ametal such as aluminium, iron, copper, tin and nickel or an alloycontaining at least one of these metals as the main constituent. Thethickness of the film or of the foil may be suitably chosen and is, forexample, approximately 0.01 to approximately 0.2 mm. It is commonpractice to degrease the surface of the metal layer before laminatingthe binder of the invention to it. The layer of oxygen-containing ornitrogen-containing polar resin (E) may also contain known additives inconventional amounts.

The invention also relates to a structure comprising respectively apolyolefin layer (F), a layer of the binder of the invention and eithera layer (E) of nitrogen-containing or oxygen-containing polar resin or ametal layer. According to another particular embodiment, the inventionrelates to a structure respectively comprising an HDPE layer, a layer ofthe binder of the invention, a layer of EVOH (or of an EVOH alloy) or alayer of polyamide (or based on polyamide), a layer of the binder of theinvention and an HDPE layer. Advantageously, it is in the form of rigidhollow bodies having a volume of 0.1 to 200 litres. The total thicknessis between 0.2 and 20 mm, the EVOH or the polyamide representing 0.5 to15% of this thickness, each binder layer 0.2 to 10% and the two HDPElayers the balance.

The MFI of the HDPE is preferably 3 to 17 g/10 min. at 190° C./21.6 kg.

The MFI of the EVOH is preferably 1 to 10 g/10 min. at 190° C./2.16 kg.

Advantageously, the external layer of HDPE may be replaced by twolayers, the outer one made of optionally coloured virgin HDPE and theother made of recycled product coming from scrap and cuttings from theextrusion-blow moulding of these hollow bodies. The thickness of theexternal HDPE layer added to the thickness of the layer of recycledmaterial is essentially the same as in the case of a single HDPEexternal layer.

These structures are useful for making petrol tanks or tubings forfilling petrol tanks.

The various layers of the structures of the invention may containadditives such as fillers, stabilizers, slip agents, antistatic agentsand fire-retardants.

The structures of the invention may be manufactured by coextrusion andextrusion-blow moulding processes, known in the field of thermoplastics.

EXAMPLES

The examples presented correspond to 5-layer structures from bottlesproduced by extrusion-blow moulding under the following conditions.

Structure of the Bottle

3 constituents, 5 layers;

HDPE/binder/EVOH/binder/HDPE;

thicknesses: 1.2/0.1/0.15 (EVOH) to 0.25 (PA)/0.1/1.2 mm;

HDPE: relative density=0.945−0.950 and MFI=5−6 g/10 min. (190° C./21.6kg);

EVOH; ethylene content=29% MFI 1.7 g/10 min. (190° C./2.16 kg).

POLYMIDE: copolyamide 6/6,6 such as the

ULTRAMID C4FN from BASF.

Type of Bottle

Cylinder (Ø=70 mm) with 2 plane faces, 0.7 litre, height=270 mm andweight=170 g.

Extrusion-blow Moulding Conditions

Temperature profiles (° C.):

Head HDPE 200 210 220 230 230 230 Binder 210 220 220 220 220 230 EVOH180 190 200 210 220 230

Tooling Diameter of the die=20 mm

Diameter of the mandrel=12 mm

Gap=4 mm

Blowing stretch ratio: approximately 3.

Measurement of the Interlayer Peel Strength

15×150 mm test-pieces cut from the plane parts of the bottle andconditioned for at least 24 hours at 23° C. and 50% RH;

cutter initiation at one of the binder/EVOH or binder/polyamideinterfaces;

“T” peel test at a crosshead speed of 50 mm/min. The peel strength,expressed in N/cm, is given by the plateau value of the peel force,excluding the starting peak. “MA” denotes maleic anhydride and theweight % of the cografted blend (A) denotes the proportion of the blendA in A+B.

TABLE 1 Formulations Example 1 Example 2 Example 3 Polymer A1 Relativedensity (g/cm³) 0.958 0.940 0.950 MFI (g/10 min./2.16 kg) 0.9 1 1 % byweight 80 75 90 Polymer A2 Comonomer propylene 1-octene propyleneRelative density (g/cm³) 0.880 0.870 0.880 MFI (g/10 min./2.16 kg) 0.2 50.2 % by weight 20 25 10 Cografted MA content (ppm) 4000 10000 6000blend A % by weight 20 25 10 Polymer B Relative density (g/cm³) 0.9340.938 0.936 MFI (g/10 min./21.6 kg) 14 20 18 A + B blend Relativedensity (g/cm³) 0.936 0.934 0.937 MFI (g/10 min./21.6 kg) 15 18 18 MAcontent (ppm) 800 2500 600 Peel strength On PA 6/6,6 (N/cm) 70 80 75 OnEVOH 50 55 55

The preceding examples can be repeated with similar success bysubstituting the generically or specifically described reactants and/oroperating conditions of this invention for those used in the precedingexamples. Also, the preceding specific embodiments are to be construedas merely illustrative, and not limitative of the remainder of thedisclosure in any way whatsoever.

The entire disclosure of all applications, patents and publications,cited above, and of corresponding French application 99/04261, arehereby incorporated by reference.

From the foregoing description, one skilled in the art can easilyascertain the essential characteristics of this invention, and withoutdeparting from the spirit and scope thereof, can make various changesand modifications of the invention to adapt it to various usages andconditions.

What is claimed is:
 1. A multilayer structure comprising a layercomprising a coextrusion binder comprising a blend comprising: 5 to 30parts of a cografted polymer (A) comprising 60-95 parts by weight of ahigh density polyethylene (A1) of relative density 0.940-0.965 and a MFIof 0.1-3 g/10 min under 2.16 kg at 190° C. and 40-5 parts by weight of apolymer (A2) of a metallocene polyethylene with 600 ppm−6% by weight ofan unsaturated carboxylic acid or its functional derivative with respectto the weight of grafted (A1) and (A2); and 95 to 70 parts of apolyethylene (B) of relative density 0.930-0.940 and a MFI of 5-100 g/10min under 2.16 kg at 190° C.; wherein a blend of the polymer (A) and thepolyethylene (B) having: a relative density of 0.930-0.940, and meltflow index measured according to ASTM D 1238 at 190° C./2.16 kg ofbetween 5 and 100 g/10 min; directly attached to said binder, a layer(E) selected from the group consisting of a layer of anitrogen-containing or oxygen-containing polar resin, a layer ofpolyamide resin, a layer of an aliphatic polyketone, a layer of asaponified ethylene-vinyl acetate copolymer (EVOM), a layer of apolyester resin, and a metal layer.
 2. A structure according to claim 1,in which either a polyolefin layer (F) or a layer (E) is directlyattached on the binder side.
 3. A structure according to claim 2,respectively comprising an HDPE layer, said layer of binder, either alayer of EVOH or of an EVOH alloy or a polyamide or polyamide-basedlayer, a second layer of said binder and an HDPE layer.
 4. A rigidhollow body made of a multilayer structure according to claim
 1. 5. Agasoline tank comprising a structure according to claim
 3. 6. Amultilayer structure according to claim 1, wherein the layer (E) is thepolyamide resin comprising at least one structural unit of PA-6; PA-6,6;PA-6,10; PA-11; PA-6/6,6; or PA-12.
 7. A multilayer structure accordingto claim 1, wherein the layer (E) is the saponified ethylene-vinylacetate copolymer having a degree of saponification of about 90-100 mol%.
 8. A multilayer structure according to claim 1, wherein the layer (E)is the polyester resin of polyethylene terephthalate, polybutyleneterephthalate, polyethylene naphthenate, or a blend thereof.
 9. Amultiplayer structure according to claim 1, wherein the layer (E) is ametal of aluminum, iron, copper, tin, nickel, or alloy thereof.
 10. Abinder according to claim 1, wherein the relative density of thepolyethylene (A1) is 0.940-0.958.
 11. A binder according to claim 1,wherein the polyethylene (B) has a relative density of 0.934-0.938. 12.A coextrusion binder according to claim 1, wherein said unsaturatedcarboxylic acid has 2 to 20 carbon atoms.
 13. A coextrusion binderaccording to claim 1, wherein said unsaturated carboxylic acid is anunsaturated dicarboxylic acid having 4 to 10 carbon atoms.
 14. Acoextrusion binder according to claim 1, wherein the binder contains 5to 20 parts by weight of (A) per 95 to 80 parts by weight of (B).
 15. Amultilayer structure comprising a layer comprising a coextrusion binderproduced by a process comprising blending: 5 to 30 parts by weight of apolymer (A) comprising cografting a blend of a polyethylene (A1) ofrelative density between 0.935 and 0.980 and of a polymer (A2) of ametallocene polyethylene with 600 ppm−6% by weight of an unsaturatedcarboxylic acid or its functional derivative with respect to the weightof grafted (A1) and (A2); and 95 to 70 parts by weight of a polyethylene(B) of relative density between 0.930 and 0.950; the polyethylene (B)having: a relative density between 0.930 and 0.950, a content of graftedunsaturated carboxylic acid of between 30 and 10,000 ppm, and melt flowindex measured according to ASTM D 1238 at 190° C./2.16 kg of between 5and 100; directly attached to said binder, a layer (E) selected from thegroup consisting of a layer of a nitrogen-containing oroxygen-containing polar resin, a layer of polyamide resin, a layer of analiphatic polyketone, a layer of a saponified ethylene-vinyl acetatecopolymer (EVOH), a layer of polyester resin, and a metal layer.
 16. Abinder according to claim 15, in which the relative density of thepolymer (A)+the polyethylene (B) is between 0.930 and 0.940.
 17. Acoextrusion binder according to claim 15, wherein the polyethylene (A1)is a polyethylene homopolymer or an ethylene copolymer with a comonomerof an α-olefin having from 3-30 carbon atoms, an ester of an unsaturatedcarboxylic acid, or a vinyl ester of a saturated carboxylic acid.
 18. Abinder according to claim 15, wherein the relative density of thepolyethylene (A1) is 0.940-0.965.
 19. A coextrusion binder according toclaim 15, wherein the amounts of (A1) and (A2) are 60 to 95 parts byweight of (A1) for 40 to 5 parts by weight of (A2).
 20. A coextrusionbinder according to claim 17, wherein said ester of an unsaturatedcarboxylic acid is an alkyl (meth)acrylate wherein the alkyl group has 1to 24 carbon atoms.
 21. A coextrusion binder according to claim 17,wherein said comonomer is propylene, 1-butene, 1-pentene,3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene,1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene,1-octadecene, 1-eicocene, 1-dococene, 1-tetracocene, 1-hexacocene,1-octacocene, 1-triacontene, methyl methacrylate, ethyl acrylate,n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, vinylacetate, or vinyl propionate.
 22. A multilayer structure comprising alayer comprising a coextrusion binder consisting essentially of: 5 to 30parts of a polymer (A) comprising a blend of a polyethylene (A1) ofrelative density between 0.935 and 0.980 and of a polymer (A2) ametallocene polyethylene with 600 ppm−6% by weight of an unsaturatedcarboxylic acid or its functional derivative with respect to the weightof cografted (A1) and (A2); and 95 to 70 parts of a polyethylene (B) ofrelative density between 0.930 and 0.950; the blend of the polymer (A)and the polyethylene (B) having: a relative density between 0.930 and0.950, a content of grafted unsaturated carboxylic acid of between 30and 10,000 ppm, and a melt flow index measured according to ASTM D 1238at 190° C./21.6 kg of between 5 and 100; directly attached to saidbinder, a layer (E) selected from the group consisting of a layer of anitrogen-containing or oxygen-containing polar resin, a layer ofpolyamide resin, a layer of an aliphatic polyketone, a layer of asaponified ethylene-vinyl acetate copolymer (EVOH), a layer of apolyester resin, and a metal layer.